1. Field of the Invention
This invention relates to a process for electrochemical fluorination wherein strict anode potential control is maintained, and to a nickel foam electrode suitable for use in such a process.
Fluorinated compounds have many uses and applications. Thus, trifluoroacetic acid, the most readily available perfluorocarboxylic acid, is used as the starting point in the synthesis of many trifluoromethyl derivatives especially in the dyestuffs and pharmaceutical industries. The acid is also used, together with its anhydride, as a solvent in several esterification and condensation reactions. The introduction of fluorine into small molecules can also result in the production of precursors for polymeric materials.
Fluorocarbon derivatives, and in particular substances consisting of an aliphatic perfluorocarbon chain containing a conventional organic grouping (e.g. alcohol, carboxylic or sulphonic acid), are of special interest because of their dual nature. The chemical inertia, the hydrophobicity and organophobicity of perfluorinated parts of these molecules, in association with the very reactive groupings, give them unusual and very useful surface-active properties with respect to aqueous media, and liquid and solid organic media.
These characteristics have resulted in such compounds being used in various fields, e.g. textile finishes, leather treatment, paper finishes, firefighting, polishes, metal treatment (to produce a protective layer), and electroplating.